I don't really get what you mean by unidentifiable type. Have never seen that. Do you mean where it useally says eg. mp3 or avi

If that's the case then I would try deleting the preference folder to see if that helps. Step 2,3 and note in this thread:

http://www.gnutellaforums.com/showthread.php?t=36420

Important: When you delete the preference folder you will have to set up Limewire from scratch. You lose all settings. Also the 'days to keep incomplete files' reverts back to 7, so if you have any incompletes that you have been trying to get for a while, then copy the incomplete folder to another location before deleting, just incase something goes wrong. Then after changing the 'days to....' back, replace the (new) incomplete folder whilst Limewire is closed.